Duane K. McCullough

Images of Mangrove tree island information in Flrida Bay
Mangrove tree island information in Florida Bay

Roughly 90% of the islands in this portion of Florida Bay are made up of four kinds of trees. Three of which are the mangrove species -- the Red Mangrove, the Black Mangrove and the White Mangrove. Another tree found on the islands of the bay is the Buttonwood tree. The hard dense tropical wood of the Buttonwood tree, was once used to make buttons for clothing and also has a seed pod that looks like a small button.

But the most numerous tree along the edges of the island in Florida Bay is the Red Mangrove. The early natives called the Red Mangrove the "walking tree" because of the illusionary concept in which the grayish red tree roots seem to walk away from themselves overtime as the prop roots grow outward and fall downward from other roots and branches.

The Red Mangrove has a seed pod shaped like a curved green pointed stick that is attached to a small brown fruit and stem growing out of some branches with dark green leaves. This seed pod falls from the tree branch and floats until it finds a shallow muddy or sandy area where it will sprout roots and branches to form a small mangrove island overtime. If not knocked over by large storm waves, a seed pod could grow into a small five by five foot island in about a decade or two. Other storm events like lightning and waterspout events can also reshape the mangrove islands overtime.

While the Red Mangrove tree begins the island building process, other trees like the Black Mangrove tree -- together with the White Mangrove tree and the Buttonwood tree, take over the process and help build the interior of the islands. Unlike the Red Mangrove tree with roots growing out and downward, Black Mangrove trees have feeder roots leading outward from their trunks to many small upward growing roots that help collect decaying tree matter overtime.

The leaves of the White Mangrove tree are smaller and more rounded than Red Mangrove tree leafs. They appear somewhat olive-green whereas Black Mangrove and Buttonwood tree leafs appear in a shades of gray-green.

All mangrove trees are able to make freshwater from saltwater in that they continually sacrifice about 5% of their leaves to rid the salt in their system which is absorbed from the seawater they grow from. In fact, although there are many plants that grow in seawater, mangrove trees are the only trees that live in saltwater. When the "sacrificial yellow leaf" falls from the mangrove tree, it takes with it much of the acidic sea salts and the remaining leaves are left with almost freshwater in them for growth.

Buttonwood trees do not have the "sacrificial yellow leaf" like the mangrove trees do -- but are very tolerant of a salty environment. As mentioned earlier, the hard dense tropical wood of the Buttonwood tree is similar to other hardwood trees in the Florida Keys, such as the Ironwood and Lignum Vitae trees.

Known as the "tree of life", the Lignum Vitae tree is rare and slow growing. In fact, the wood from the Lignum Vitae tree is still used as ball bearing material aboard American military nuclear submarines because it is very durable and operates quietly. The wood is so dense with manganese and iron that it actually sinks in water -- the material is like a metal fiber compound.

Another natural tree also found on many islands in Florida Bay is the Seagrape tree which has a large rounded leaf and produces a sweet grape-like berry that when ripe can be used to make jelly, jam or wine.

It's nice to discover something sweet to eat growing out here in this sometimes harsh acidic environment like the Seagrape tree.

Some larger islands may also have the Gumbo-limbo tree growing on them. These trees are also know as "the naked Indian" or the "tourist tree" because their skin-like bark is very red like a red skinned native Indian or sunburnt tourist with flaky skin.

Along the shore of Key Largo during the late Spring can be found the bright-red blossoms of the Royal Poinciana, together with the Tamarind, Jamaica Dogwood, Strangler Fig, Sapodilla, Mahogany and Key Lime trees. When we return to the resort after the tour, take the time to walk the trial in the woods near the dock and you will notice some of these trees. One tree you should be careful of is the Poisonwood tree because of its namesake -- it has what looks like motor oil splotches on its trunk and can leave a nasty rash if you come in contact with its toxic sap.

Of course we have tropical palm trees here in the Florida Keys -- the four basic kinds include the Coconut Palm, with its coconuts and long big multifaceted leaves; the Thatch Palm, which looks somewhat like the Cabbage Palm but with a smaller trunk -- and the Royal Palm, which grow very strait and tall and have a trunk that looks as if it made out of poured concrete.

I should also mention that yet another kind of tree can be found on some nearby islands in the bay. If you look over to our left in the distance, those tall trees on that island are called Casuarinas or Australian Pine trees. These trees are not native to the area and about once a decade the governments attempts to kill them with herbicide because they can take over the island like a weed in no time. They are considered an exotic invasive species because they blow over easy in lose soil, they burn easy -- and they leave a bed of acidic needles near them that will not let other plants to take root.

Many islands in the Caribbean and other tropical places in the world have them -- especially in the Bahamas, where on some islands nothing but these trees are found growing. Casuarinas appear on the some of islands in Florida Bay because their seeds are carried within bird droppings.

There are many more types of trees found here in the Florida Keys, but the ones Iíve mentioned are the ones we may see out here in Florida Bay during our tour.

Speaking of trees out here in Florida Bay, nearly five centuries ago, when Spanish explorers first mapped the realm of what is now the Florida Keys, they named the area "Cayos de los Martyres" which can be understood as meaning "small rocky islands of the marine trees".

How the Spanish word of "Cayo" which means "small rocky island" became the English word "Key" over time is fairly easy to understand because the word makes the same sound. However, the novel concept in which the word "martyres" means "marine trees" is a new translation that has multiple meaning.

For example, if the word "martyres" is separated into two Latin words, the collective words may not only mean the "marine trees" -- as in the mangrove tree islands of the Florida Keys, but also the term "sea forest" -- as in the coral reefs of the Florida Keys which looked like wild areas of aquatic foliage to the early seafarers who first mapped the area.

In any case, the mangrove tree islands and coral forest of the Florida Keys are a very unique realm awaiting discovery. To better understand this realm, a quick geological and hydrological overview is in order.


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